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Abstract The unique optical properties of transition metal dichalcogenide (TMD) monolayers have attracted significant attention for both photonics applications and fundamental studies of low-dimensional systems. TMD monolayers of high optical quality, however, have been limited to micron-sized flakes produced by low-throughput and labour-intensive processes, whereas large-area films are often affected by surface defects and large inhomogeneity. Here we report a rapid and reliable method to synthesize macroscopic-scale TMD monolayers of uniform, high optical quality. Using 1-dodecanol encapsulation combined with gold-tape-assisted exfoliation, we obtain monolayers with lateral size > 1 mm, exhibiting exciton energy, linewidth, and quantum yield uniform over the whole area and close to those of high-quality micron-sized flakes. We tentatively associate the role of the two molecular encapsulating layers as isolating the TMD from the substrate and passivating the chalcogen vacancies, respectively. We demonstrate the utility of our encapsulated monolayers by scalable integration with an array of photonic crystal cavities, creating polariton arrays with enhanced light-matter coupling strength. This work provides a pathway to achieving high-quality two-dimensional materials over large areas, enabling research and technology development beyond individual micron-sized devices. 

Abstract Semiconductor microcavities with a high quality‐factor are an important component for photonics research and technology, especially in the strong coupling regime. While van der Waals semiconductors have emerged as an interesting platform for photonics due to their strong exciton–photon interaction strength and engineering flexibility, incorporating them in photonic devices requires heterogeneous integration and remains a challenge. This study demonstrates a method to assemble high quality factor microcavities for van der Waals materials, using high reflectance top mirrors which, similar to van der Waals materials themselves, can be nondestructively and reliably peeled off the substrate and transferred onto the rest of the device. Microcavities are created with quality factors consistently above 2000 and up to 11000 ± 800; and the strong coupling regime is demonstrated. The method can be generalized to other types of heterogeneously integrated photonic structures and will facilitate research on cavity quantum electrodynamic and photonic systems using van der Waals materials.